According to many local building codes, electrical wiring which is not enclosed within a building's walls must be protected in an armored sheath. This is normally done by running the wire through either a relatively rigid, although shapable, metallic conduit or by encasing the wire in a flexible armor sheath. This flexible armor sheath is commonly referred to as "BX", which is supplied with the necessary wire conductors already encased therein, or "FLEX", which is a flexible armor sheath into which the necessary wires are introduced on site. Most commonly, these flexible armor sheaths are constructed of a helically-wound metallic, or reinforced nonmetallic, material. Because of its helical construction, such an armor sheath is difficult to cut with ordinary tools.
Various tools, such as those shown in U.S. Pat. Nos. 2,176,646 and 3,453,917, have been designed to provide a longitudinal cut along such helically-wound cable armor. C. A. Thatcher (U.S. Pat. No. 2,176,646) discloses a tool for clamping cable armor in place and providing a longitudinal cut in the sheath. This device is relatively large and is cumbersome for a worker to carry while on a jobsite. It is also too large to conveniently be used in close quarters.
F. J. Perry (U.S. Pat. No. 3,453,917) shows a rotary cutter for flexible cable armor which clamps the sheath into place and creates a longitudinal cut.
Each of the above-described devices is limited to a specific use and does not allow the user to select the angle at which the sheath is cut. Despite the disclosure of these prior art devices, the heretofore most common method of cutting such cable armor is with an ordinary hack saw. The cable sheath is held in one hand while the other hand directs the saw diagonally across a helical strand of the sheath until it is completely cut through one turn of the helix. The sheath is then bent away from the cut line to separate the helical turns. Although a hack saw has a wide variety of alternative uses, it is still relatively large to be carried on a worker's tool belt and can be difficult to use in the close quarters. Also, this method of cutting is slow and fatiquing to the worker. The hack saw blade is prone to slipping from its position on the sheath, resulting in a jagged cut edge or injury to the worker's fingers.